Fabián Pina Amargós

An experiment of fish spillover from a marine reserve in Cuba

Several studies on adult fish movement from marine protected areas to zones open to fishing activity conclude spillover is present, but most of these investigations use indirect evidence and small-sized species of little commercial importance. This paper reports the effects of manipulating a density gradient on movements of large-sized and commercially-important fish across “Jardines de la Reina” Marine Reserve boundaries, using tagging methods and visual census. Tagging was carried out using dart tags and modified spearguns at an experimental and a control site. Density of fish was experimentally manipulated on the unprotected side of the boundary. Before experimental manipulation, fish density was similar in both experimental and control sites and on both sides of the boundaries. After manipulation, fish density in the unprotected side of experimental site declined dramatically and a strong gradient was established through the boundary. One month later, this forced gradient disappeared, returning to the situation at the beginning of the study. This last result is due to spillover effect: the mean distance traveled by fish increased 1.5 times (mean from below 200xa0m to more than 300xa0m), the mean emigration rate doubled and the immigration rate decreased, allowing density levels to recover after manipulation.

Efecto del dragado de un canal de comunicación al mar (estero) sobre la asociación de peces en la Laguna Larga, Cayo Coco, Cuba

Fish community and habitat of the estuarine channel connecting to the sea at Laguna Larga were characterized before and after the dredging conducted in 2012. For this purpose, the channel was divided into four sections: two initial sections near the sea (IA, IB) and two final sections near the lagoon (FA, FB). A total of 112 visual surveys were conducted by free diving. Shelter area, shade, water temperature, salinity, as well as current depth and velocity were measured in order to characterize the habitat. Spatial and temporal distribution of fish, species richness, density, and relative frequency were determined in each section, and results were related to habitat characteristics. A total of 22 species of fish distributed in 14 families were recorded.xa0 The following were the dominant species: Abudefduf saxatilis, Halichoeres bivittatus, Stegastes leucostictus, and Lutjanus griseus. Fish density and richness were higher at the beginning of the channel than at the end, particularly Lutjanus griseus, which changed its niche preferences from the end of the channel (FB) to the beginning (IB). In addition, fish communities varied spatially and temporally. The restoration process resulted in decreased availability of shelter and consequently determined the decrease in density and species richness at the beginning of the channel. The most drastic changes in fish spatial and temporal pattern were associated with the final sections of the canal, which suffered the greatest changes in habitat.